This invention relates to a machining tool with a grinding function equipped with an electric discharge truing and dressing apparatus of a metal bond grinding wheel for grinding a workpiece.
This invention also relates to a machine tool having a grinding function capable of performing a center work machining and the like, and capable of dressing in a state where a tool for grinding is installed in a tool rest, a dressing apparatus being used for it and the dressing method, and grinding tool.
Furthermore, this invention relates to a chip collecting apparatus used for a machine tool such as a lathe, and a method of collecting chips.
In recent years, ceramic materials or the like have received a lot of attention because of their characteristics, such as resistance to high temperature and resistance to wear, and have been applied to various kinds of devices. Therefore, developments and proposals have been made in machining arts and techniques so that ceramic materials can be cut and ground as easily as iron materials can. The present inventors have tried to grind a hard and fragile material using a cast iron bond diamond grinding wheel and a machining center. As a result, they have confirmed that highly efficient machining of ceramics and cemented carbide or sintered hard alloy was effective.
In order to perform the grinding machining by a cast iron bond diamond grinding wheel with high accuracy and efficiency, however, truing and dressing is indispensable on the body of a machining tool. Heretofore, it was said that no effective truing and dressing methods were present with respect to a metal bond grinding wheel. The present inventors have proposed a wire electric discharge truing and dressing method on the body of a machining tool.
The illustration of FIGS. 4 and 5 show the principle thereof, in which an electric discharge machining is performed between a wire electrode 95 and a metal bond grinding wheel 90 using a wire cut electric discharge power source 96. Since electric discharge truing and dressing is performed on the body of a machining tool, there can be obtained a high accuracy with minimal errors. The present inventors have proposed a truing center in which the afore-mentioned dressing method is applied.
Furthermore, the present inventors have proposed an electric discharge truing by a block-like electrode as an improvement of an electric discharge truing and dressing method by the afore-mentioned wire electric discharge. The present inventors also have proposed a method for performing an electric discharge truing and dressing of a metal bond grinding wheel mounted on a tool spindle using a generated electrode, obtained by cutting an electrode into a desired configuration with a tool mounted on a tool spindle.
However, since the machining with the wire electrode required the use of a wire electrode, the electric discharge partially takes place, and an average electric current is limited. Therefore, the removal efficiency of the metal portion of the metal bond grinding wheel became insufficient and the truing and dressing efficiency became worse. In addition, since the wire was limited in thickness, the shape truing of the grinding wheel was limited in configuration. For example, there arose such problems as an irregularity having a sharp angle, or a complex configuration could not be generated.
The proposal of the electric discharge truing with a block-like electrode were all no more than the proposals of the principle of the electric discharge truing and dressing method. The proposals were still insufficient in solving the problems relating to the structure and arrangement of the truing and dressing apparatus, particularly in the respect that they were applied to a turning center for grinding and machining a cylindrical workpiece with high efficiency. That is, in a conventional special machining such as electro-chemical machining, one-to-one automatic machining was available, but there was no such machine in which workpiece W having various configurations could be continuously machined without manpower. Therefore, in the prior art, it was impossible to attain automation.
And heretofore a proposal was advanced relating to a dressing apparatus by which truing and the like are performed by means by electric discharge machining toward a grinding stone portion which is blinded. In the prior art, in order to perform truing and the like by means by the dressing apparatus, rough truing and dressing are performed on the grinding stone portion which is blinded by using a machining electrode for rough machining at first. Thereafter, the machining electrode for rough machining is detached from the dressing apparatus and the machining electrode for finishing machining is attached to it in turn. In this way, the finishing truing and dressing are performed.
However, in this method it is necessary that the machining electrode for rough machining is detached after rough truing toward the grinding stone portion of a grinding tool and the machining electrode for finishing machining is attached. It is convenient that finishing truing and the like cannot be performed immediately.
Electricity needs to be fed to a grinding stone portion via an electrode by connecting the electrode with the grinding stone portion so as to be free to connect and separate therefrom. But, such an art is far from development.
Moreover, in the prior art when a center work machining and the like are performed by means of a complex machine tool, one end portion of a workpiece is held by the spindle of the machine tool via a chuck, and the other end portion is supported by the center of a tailstock. In this state, a workpiece is cut in a predetermined form by a tool installed in a tool rest.
In recent years, the proposal, to perform grinding machining toward a workpiece by installing a tool for grinding in a tool rest in a complex machine tool, has been advanced. But, in case blinding arises in a grinding tool, it is necessary to perform dressing. Then a method in which dressing is performed by electric discharge machining toward the grinding stone which is blinded is adopted in the prior art. Dressing is performed in such a manner that the tool for grinding which is blinded is detached from the tool rest and is attached to an electrical discharge machine provided separately from the complex machine tool.
However, according to this method, a worker must perform the operations of the detachment and attachment of a grinding tool whenever dressing is performed. And, it is difficult to perform a grinding activity automatically without manpower in the complex machine tool. Then, it is thinkable that a dressing apparatus is disposed on the machine body of the complex machine tool and dressing is performed in a state that the grinding tool is installed on the tool rest by means of the apparatus. In this method, a new problem occurs. That is, there is a situation in which the machining cannot be performed because of the interference between the tailstock, which is provided free to move on the machine body in the same manner as the dressing apparatus, and the dressing apparatus, when center workpiece machining and the like is performed.
In a conventional machine tool such as a lathe, when the machining is performed on workpieces of different kinds of materials, differentiation of machining is not present, except for specific cases. Therefore, when the chip produced is collected it mixes with different kinds of chips.
This method is defective in the complication of the separation and classification of chips, for the object of effectively utilizing resources. In the case where a workpiece machined is completely different in character, such as metal and ceramic, a chip collecting apparatus capable of collecting and classifying the chip produced from the first is desirable.